Anorectal Malformation

  • Etiology: congenital, is high if rectal pouch is above levator sling, is low if rectal pouch is below levator sling
  • Imaging: high atresia – rectourethral fistula demonstrated by colostomy injection, enterolith – intraluminal meconium may calcify when mixed with urine from rectourethral fistula
  • Complications: rectoperinal fistula – 95% of anorectal malformation have recto-perineal fistula, in male 50% goes to urethra + 30% goes to seminal vesicle, in female 40% goes to urethra + 30% goes to vestibule + 25% goes to vagina, often have continence issues post op
  • Clinical: have VACTERL syndrome which consists of Vertebral body segmentation anomalies, Anal atresia, Cardiac anomalies, TracheoEsophageal fistula, Renal anomalies, and Limb anomalies (radial ray hypoplasia)
  • Radiology management to assess for associated VACTERL defects:
    — Spine and sacrum – AP+lateral spine radiography including AP + lateral sacrum, spinal US for tethered cord, pelvic MR if sacral mass detected (sacral teratoma or anterior meningocele)
    — Congenital heart disease – echocardiogram
    — Esophageal atresia – nasogastric tube placement then CXR + AXR
    — Genitourinary – renal and bladder US
    — Limb radiographs as clinically indicated
    — In female with cloaca, get renal + pelvis US to look for hydrocolpos
    — Assess for recto-urethral fistula in male prior to repair with distal colostogram
    — Assess cloaca prior to repair with 3D cloacagram

Radiology Cases of Anorectal Malformation

AXR of anorectal malformation
AXR shows a distal bowel obstruction with gas down to the rectum. On physical exam the anus was absent.
AXR of anorectal malformation
AXR (above) shows multiple dilated loops of bowel within the abdomen that are progressively more dilated as they near the rectum. Prone cross-table lateral radiograph of the abdomen obtained after 10 minutes in the prone position (below) with a radio-opaque BB on the anus shows a short distance between the anus and the gas in the rectum.
AXR of cloacal exstrophy
AXR AP shows diastasis of the symphysis pubis and multiple spinal segmentation defects while the AXR lateral shows a small amount of bowel herniated anterior to the abdomen and inferior to the umbilicus along with a large skin covered spinal dysraphism posteriorly and a radioopaque marker being held in place over where the anus should be.
AXR of cloacal exstrophy
AXR shows diastasis of the symphysis pubis, multiple loops of bowel outside the contour of the abdomen inferiorly, and multiple segmentation anomalies in the lower lumbar spine and sacrum.

Clinical Cases of Anorectal Malformation

Clinical image of anorectal malformation / imperforate anus
Clinical image shows absence of the anal orifice. There is a good buttock cleft. There were no perineal or scrotal raphe fistula seen.
Clinical image of anorectal malformation
Clinical image shows meconium exiting the urethral meatus.
Clinical image of anorectal malformation
Clinical image shows normal appearing external genitalia, but no anus. Examination of the vaginal introitus reveals a rectal fistula to the posterior vaginal fourchette in the midline, located just inferior to the vagina.